Python class creation like C#

Question

Does Python have any syntax that allows you to create an instance of a class and set property values on it within the same statement

You can do this in C# like this

StudentName student2 = new StudentName
{
    FirstName = "Craig",
    LastName = "Playstead",
};

Is there an equivalent in Python?

You can define defaults in `__init__` method which is constructor equivalent — cymruu, Nov 29 '18 at 11:01
I need to be able to set specific values for each instance, being able to do this in a single statement would greatly simplify my code. — Sprotty, Nov 29 '18 at 11:04
check out `_slots_` https://stackoverflow.com/a/28059785/1344855 — dh762, Nov 29 '18 at 11:06
@toefftoefftoeff `__slots__` is an advanced feature that's very rarely needed in real life. I'm not sure how it would apply here much, anyway. — AKX, Nov 29 '18 at 11:11

score 6 · Accepted Answer · edited Nov 29 '18 at 11:23

Not really. The Pythonic ways to express this might be one of the following.

A regular old class

class StudentName:
    def __init__(self, first_name, last_name):
        self.first_name = first_name
        self.last_name = last_name

student2 = StudentName(first_name="Craig", last_name="Playstead")

(You can also add a , *, argument after self to force users to spell out the keyword names see Keyword (Named) Arguments in Python.)

A namedtuple

import collections
StudentName = collections.namedtuple("StudentName", "first_name last_name")

student2 = StudentName(first_name="Craig", last_name="Playstead")

Namedtuples also act like tuples, so you can use student2[0] to access first_name and [1] for last_name.

A `dataclass` (Python 3.7+)

import dataclasses

@dataclasses.dataclass
class StudentName:
    first_name: str
    last_name: str

student2 = StudentName(first_name="Craig", last_name="Playstead")

Thanks. I can make it worked with named parameters, I have control of the classes being created so I can add all the properties in as optional parameters. The dataclass solution looks pretty neat, but I think the 3.7 requirement is to limiting for us. — Sprotty, Nov 29 '18 at 11:17

score 1 · Answer 2 · edited Nov 29 '18 at 11:08

class StudentName:
    def __init__(self, firstname, lastname):
         self.firstname = firstname
         self.lastname = lastname


name = StudentName('firstname', 'lastname')

If you want to specifically set which property is which in the constructor:

class StudentName:
    def __init__(self, firstname='', lastname=''):
         self.firstname = firstname
         self.lastname = lastname


name = StudentName(firstname='firstname', lastname='lastname')

You can then also create a StudentName like so: StudentName(). His first and lastname would be ''.

score 1 · Answer 3 · answered Nov 29 '18 at 11:08

You can define defaults in __init__ method which is constructor equivalent

class Student():
  def __init__(self, firstname, lastname):
    self.firstname = firstname
    self.lastname = lastname

  def __str__(self):
     return "My name is {} {}".format(self.firstname, self.lastname)

s1 = Student("John", "Smith")
print(s1)

Python class creation like C#

3 Answers3

A regular old class

A namedtuple

A dataclass (Python 3.7+)

A `dataclass` (Python 3.7+)